I wouldn't worry so much about what the "real" meaning of BS is. People clearly mean different things by it, and there's no reason to think there's one true answer. The interesting question is "Is the concept called 'bullshit' by Frankfurt a coherent idea that's useful for understanding the world?". If so, then in the present context we can call it "bullshit in the sense of Frankfurt", or "bullshit" for short, and get on with the non-semantical discussion.